1. Field of the Art
This invention relates to a telescope lens tube protector to be fitted on lens tubes of a monocular or binocular telescope for the purpose of protecting the lens tubes from shocks of collisional impacts or the like.
2. Prior Art
As for an example of telescopes in general, a binocular telescope or field glass is usually put in a shock-free case of an exclusive design when not used. As well known, ordinarily a strap is attached to each field glass for the convenience of the use who moves around with a field glass in an outdoor activity, permitting the user to hang down the field glass from his or her neck or shoulder while moving, looking for a bird watching spot or for other observation spot. Accordingly, when moving from one spot to another, the viewer is not necessarily required to carry the field glass in his or her hand. Nevertheless, taking into consideration that in many cases telescopes like field glasses are carried by viewers for a long time in outdoor activities, no matter whether they are hung from a neck or carried in a hand, there has been a trend for reducing the weight of telescopes to lessen the burdens in portage, either by forming lens tubes from a light-weight synthetic resin material or by reducing the wall thickness of lens tubes as much as possible in case lens tubes are made of a metal or metallic material.
In case the wall thickness of field glass lens tubes is reduced for a weight reduction, it will invariably give rise to a problem of physical weakness to shocks of collisional impacts because they are mainly intended for use in outdoor activities in which there are many possibilities of the field glasses being hit against something or inadvertently dropped on the ground as they are repeatedly put on and off the eyes of viewers in the course of a trip through a field. Namely, when subjected to collisional impacts or the like, relatively thin-walled lens tubes are susceptible to damages including deformations and fractures. In case lens tubes are damaged, deformed or fractured to a serious degree, the field glasses will not function properly even if lenses remain safely in an undamaged state. Besides, one would face a serious damage in case impacts directly act on end portions of lens tubes which can be easily deformed or fractured even by impacts of a smaller magnitude.
In this connection, it has been known in the art to cover or coat telescopic lens tubes with rubber or similar resilient material to provide protection against collisional impacts without increasing the size or weight of telescopes as a whole. However, in many cases simple rubber covering or coating of this sort is found to be unable to absorb shocks or impacts effectively, particularly, unable to prevent a deformation or damage to an end portion of a lens tube when it is hit against a hard object.